SQLMentor
From your first SELECT to recursive CTEs and window functions — structured, practical, and built for real-world use.
From SELECT basics to performance tuning — the complete Oracle SQL path
Introduction to SQL, basic SELECT queries, filtering with WHERE, and essential operators.
Aggregate functions, joins, and subqueries — the building blocks of every SQL statement.
Constraints, DDL, DML, views — defining and manipulating the structure of your database.
Index types, query plans, hints, and strategies for writing high-performance SQL.
Window functions, CTEs, stored procedures, performance tuning, and interview mastery.
JSONB, MVCC, index types, PL/pgSQL — deep PostgreSQL mastery
PostgreSQL intro, psql CLI, and the full range of native data types including arrays.
SELECT with LATERAL joins, subqueries, CTEs, window functions, and set operations.
DML with RETURNING, UPSERT (ON CONFLICT), transactions, schemas, and sequences.
Index types (B-Tree, GIN, BRIN), EXPLAIN plans, views, and materialized views.
VACUUM, ANALYZE, JSONB operations, arrays, triggers, and PL/pgSQL procedures.
Oracle's procedural extension — packages, cursors, triggers, BULK COLLECT
Block structure, variables, constants, conditional logic, and loop constructs.
Embedding SQL, implicit cursors, explicit cursors with FOR UPDATE, and REF cursors.
Records, collections (nested tables, varrays), BULK COLLECT, and FORALL for performance.
Stored procedures, functions, packages, and structured exception handling.
Triggers, dynamic SQL, autonomous transactions, object types, pipelined functions, and built-in packages.
Microsoft T-SQL — APPLY, MERGE, CTEs, execution plans, and more
SQL Server intro, SSMS tooling, data types, SELECT with TOP and OFFSET-FETCH.
Joins with APPLY, subqueries, CTEs, window functions, and set operations.
DML with OUTPUT, MERGE statement, transactions, schemas, constraints, and IDENTITY.
Variables, TRY/CATCH, stored procedures, UDFs, triggers, views, and JSON/XML.
Index strategies, execution plans, query tuning, statistics, and maintenance tasks.
Oracle bulk-load utility — control files, direct path, LOBs, external tables
Architecture, the sqlldr CLI, control file structure, and LOAD DATA basics.
Field specs, record formats, conventional path, and direct path loading modes.
Load modes, CSV/TSV, fixed-width, date formats, LOBs, WHEN clause, and multi-table loads.
NULLIF/FILLER, SQL functions, BAD/DISCARD files, performance tuning, and external tables.
Enterprise SQL on IBM DB2 — OLAP, XML, optimization, and administration
DB2 architecture, data types, DDL, and essential SELECT query patterns.
Joins, subqueries, CTEs, window functions, OLAP extensions, and grouping sets.
DML operations, stored procedures, user-defined functions, triggers, and XML support.
Indexes, EXPLAIN, RUNSTATS, transactions, security, partitioning, and DB2 cheatsheet.
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